Publication

Plaquette valence-bond crystal in the frustrated Heisenberg quantum antiferromagnet on the square lattice

Publications associées (31)

First-order Neel to columnar valence bond solid transition in a model square-lattice S=1 antiferromagnet

We study the Neel to fourfold columnar valence bond solid (cVBS) quantum phase transition in a sign-free S = 1 square-lattice model. This is the same kind of transition that for S = 1/2 has been argued to realize the prototypical deconfined critical point. ...

AMER PHYSICAL SOC2020

Exchange Interactions Mediated by Nonmagnetic Cations in Double Perovskites

Oleg Yazyev, Henrik Moodysson Rønnow, Peter Babkevich, Vamshi Mohan Katukuri, Sami Juhani Vasala

Establishing the physical mechanism governing exchange interactions is fundamental for exploring exotic phases such as quantum spin liquids in real materials. In this Letter, we address exchange interactions in Sr2CuTexW1-xO6, a series of double perovskite ...

AMER PHYSICAL SOC2020

Temperature dependence of the(pi,0)anomaly in the excitation spectrum of the 2D quantum Heisenberg antiferromagnet

Martin Mourigal, Henrik Moodysson Rønnow, Goran Nilsen

It is well established that in the low-temperature limit, the two-dimensional quantum Heisenberg antiferromagnet on a square lattice (2DQHAFSL) exhibits an anomaly in its spectrum at short-wavelengths on the zone-boundary. In the vicinity of the (pi, 0) po ...

IOP PUBLISHING LTD2020

Structural Disorder and Magnetic Order in Atomically Thin Crystals

Michele Pizzochero

This Thesis is mainly devoted to the exploration of the structural disorder and magnetic order in two-dimensional crystals by means of first-principles methodologies. Firstly, we present a comparative study of defect formation in the semiconducting 2H and ...

EPFL2020

Exact diagonalization study of the Hubbard-parametrized four-spin ring exchange model on a square lattice

Henrik Moodysson Rønnow, Noore Elahi Shaik, Sofie Janas

We have used exact numerical diagonalization to study the excitation spectrum and the dynamic spin correlations in the s = 1/2 next-next-nearest-neighbor Heisenberg antiferromagnet on the square lattice, with additional four-spin ring exchange from higher- ...

AMER PHYSICAL SOC2019

Antiferroelectric antiferromagnetic type-I multiferroic Cu9O2(SeO3)(4)Cl-6

Helmuth Berger, Wei Li

We report that Cu9O2(SeO3)(4)Cl-6 is a new multiferroic compound. Comprehensive studies of this compound have been carried out on single crystals as well as polycrystalline samples. Magnetic susceptibility chi and specific heat C with H parallel to c axis ...

AMER PHYSICAL SOC2019

Frustration and Randomness : Magnetic Studies of Organic Quantum Spin Liquids

Péter Szirmai

Spin systems with strong magnetic interactions might remain disordered avoiding conventional magnetic long-range ordering due to zero-point quantum fluctuations, and supporting a Quantum Spin Liquid (QSL) state. Long-range quantum entanglement in QSLs prom ...

EPFL2018

Non-Abelian chiral spin liquid in a quantum antiferromagnet revealed by an iPEPS study

Abelian and non-Abelian topological phases exhibiting protected chiral edge modes are ubiquitous in the realm of the fractional quantum Hall (FQH) effect. Here, we investigate a spin-1 Hamiltonian on the square lattice which could, potentially, host the sp ...

2018

Reentrant magnetism at the borderline between long-range antiferromagnetic order and spin-glass behavior in the B-site disordered perovskite system Ca2-x SrxFeRuO6

Philip Pattison

We report on the coexistence of magnetic order and disorder in the atomically disordered double perovskites Ca2FeRuO6 and CaSrFeRuO6. Powder x-ray and neutron diffraction were used to investigate the crystal structure and magnetic ordering of these oxides. ...

AMER PHYSICAL SOC2018

J1−J2 square-lattice Heisenberg antiferromagnets with 4d1 spins: AMoOPO4Cl (A=K,Rb)

Henrik Moodysson Rønnow, Peter Babkevich

Magnetic properties of AMoOPO4Cl (A=K,Rb) with Mo5+ ions in the 4d1 electronic configuration are investigated by magnetization, heat capacity, and nuclear magnetic resonance (NMR) measurements on single crystals, combined with powder neutron diffraction ex ...

2017

Neutron spectroscopy in the layered quantum magnet SrCu₂(BO₃)₂ and in transition metal phosphorus trisulfides (MPS₃)

Diane Virginie Marie Lançon

Collective magnetic excitations are a fascinating aspect of condensed matter physics, where neutron scattering can provide valuable insight into the magnetic properties of physical realisations of model systems. This thesis focuses on the excitation spectr ...

EPFL2017